Some new integrated circuits chips have better thermal dissipation features. Once such integrated circuit (IC) package that has better thermal dissipation features is the thermally-enhanced quad flack pack (QFP). The thermally-enhanced QFP includes a heat sink or pad mounted to the bottom of the IC package that holds the IC. The heat sink is mounted to provide a thermal conduction path from the IC die to the substrate upon which the IC package is mounted. An example of a thermally-enhanced QFP is shown in U.S. Pat. No. 5,905,299 to Lucap or sold by Analog Devices, Inc. of Norwood, Mass. for example, part no. SP-240-1. In order to provide good thermal conductivity, the heat sink on the IC package needs to be mounted properly to a mounting pad on the substrate.
To ensure mounting wherein the thermal conductivity path is correct, solder must be applied over the entire surface of the heat sink and the mounting pad without voids. However, this mounting can prove difficult and sometimes, errors occur in the mounting of the thermally-enhanced QFP. Thus, a testing regiment must be employed to determine if the ICs package is mounted on the substrate properly. There are several methods of possibly doing this. One may be visual inspection. However, this may require the thermally-enhanced QFP to be removed to see how the soldering process worked. As such, visual inspection cannot be a 100% test, but rather, the product must be sampled because the part would have to be remounted or the part may be destroyed. In other instances, an X-ray machine may be used. However, X-ray inspection is more difficult because both the mounting pad and the heat sink are underneath the IC package of the IC and, as such, the X-ray has a difficult time imaging the surface upon which the heat sink is mounted. Thus, currently there is no good way of testing the mounting of a thermally-enhanced QFP that would test 100% of the parts and ensure good testing results.